In the Garden:Western Mountains and High Plains
April, 2007
Regional Report

Foiling Annual Weeds

If your landscape is like mine, then you are most likely harboring a corner or two where weeds are flourishing without human intervention. It happens every spring when we get busy doing other things, and the weeds reappear, or start from new seeds, to grow even stronger and meaner. Of all the chores in the garden, weeds seem to require the most time, energy, and attention. This steals valuable time when you'd rather be relaxing outdoors.

One of the best strategies for controlling weeds is to understand their life cycle. Weeds can be categorized as either annual or perennial; there are also biennials, which have a two-year life cycle. Knowing the life cycle of the weed can help you plan the appropriate control measures.

Annual weeds start from seed, germinate, grow to maturity, produce seed, and die out in one growing season. When young, annual weeds are easy to control by digging and pulling, and you don't leave any persistent roots behind. However, these weeds seem to get even by producing hundreds, if not thousands, of seeds that produce future generations of plants.

Timing is Everything
Downy bromegrass is a common annual weed that germinates in cool weather of the fall, overwinters in the soil, and returns in the spring. Also known as cheatgrass, this clump grass starts to invade flower beds, shrub borders, and the lawn and, if left unattended, will produce seeds and continue its invasion across the landscape. So now is a good time to pull the developing clumps when there is good moisture in the soil. This management technique will reduce the spread of this pest.

Mustards, shepherd's purse, chickweed, and annual bluegrass are among the other annual weeds that rear their heads in spring. They grow very quickly from seed to seed-producer, and will keep on growing if left unmanaged. The requirements for germination vary from seed to seed, and that ensures that all seeds don't germinate all at once, which makes it possible for some seeds to escape control measures.

One control measure for stopping seeds before they start to germinate is the application of corn gluten meal, a natural substitute for synthetic pre-emergent herbicides. It works by attacking the seeds while they are still in the ground, before the seedlings emerge from the soil. It poses no health risk to people, pets, and wildlife.

Weeds that are already up and growing will not be controlled by products made of corn gluten. The annual weeds will eventually die by the end of summer or with the first hard frost. Waiting for the weeds to die, however, does not stop them from producing more seeds. So you will have to get out there and mechanically dig or pull weeds to prevent the flowers from growing on to produce seed heads.

When it comes to weeds, you'll get much better control if you get out there and tackle the problem early. If you don't get them under control, there will come a time when you feel like the weeds are controlling you!